591 research outputs found
Remote preparation of arbitrary ensembles and quantum bit commitment
The Hughston-Jozsa-Wootters theorem shows that any finite ensemble of quantum
states can be prepared "at a distance", and it has been used to demonstrate the
insecurity of all bit commitment protocols based on finite quantum systems
without superselection rules. In this paper, we prove a generalized HJW theorem
for arbitrary ensembles of states on a C*-algebra. We then use this result to
demonstrate the insecurity of bit commitment protocols based on infinite
quantum systems, and quantum systems with Abelian superselection rules.Comment: 21 pages, LaTeX. Version 2: Proofs expanded and made more
self-contained; added an example of a bit commitment protocol with continuous
ensemble
The non-relativistic limit of (central-extended) Poincare group and some consequences for quantum actualization
The nonrelativistic limit of the centrally extended Poincar\'e group is
considered and their consequences in the modal Hamiltonian interpretation of
quantum mechanics are discussed [ O. Lombardi and M. Castagnino, Stud. Hist.
Philos. Mod. Phys 39, 380 (2008) ; J. Phys, Conf. Ser. 128, 012014 (2008) ].
Through the assumption that in quantum field theory the Casimir operators of
the Poincar\'e group actualize, the nonrelativistic limit of the latter group
yields to the actualization of the Casimir operators of the Galilei group,
which is in agreement with the actualization rule of previous versions of modal
Hamiltonian interpretation [ Ardenghi et al., Found. Phys. (submitted)
Explaining the unobserved: why quantum mechanics is not only about information
A remarkable theorem by Clifton, Bub and Halvorson (2003)(CBH) characterizes
quantum theory in terms of information--theoretic principles. According to Bub
(2004, 2005) the philosophical significance of the theorem is that quantum
theory should be regarded as a ``principle'' theory about (quantum) information
rather than a ``constructive'' theory about the dynamics of quantum systems.
Here we criticize Bub's principle approach arguing that if the mathematical
formalism of quantum mechanics remains intact then there is no escape route
from solving the measurement problem by constructive theories. We further
propose a (Wigner--type) thought experiment that we argue demonstrates that
quantum mechanics on the information--theoretic approach is incomplete.Comment: 34 Page
Temporal pixel multiplexing for simultaneous high-speed, high-resolution imaging
We introduce an imaging modality that, by offsetting pixel-exposure times during capture of a single image frame, embeds temporal information in each frame. This allows simultaneous acquisition of full-resolution images at native detector frame rates and high-speed image sequences at reduced resolution, without increasing bandwidth requirements. We demonstrate this method using macroscopic and microscopic examples, including imaging calcium transients in heart cells at 250 Hz using a 10-Hz megapixel camera
Recursive proof of the Bell-Kochen-Specker theorem in any dimension
We present a method to obtain sets of vectors proving the Bell-Kochen-Specker
theorem in dimension from a similar set in dimension (). As an application of the method we find the smallest proofs known in
dimension five (29 vectors), six (31) and seven (34), and different sets
matching the current record (36) in dimension eight.Comment: LaTeX, 7 page
Effects and Propositions
The quantum logical and quantum information-theoretic traditions have exerted
an especially powerful influence on Bub's thinking about the conceptual
foundations of quantum mechanics. This paper discusses both the quantum logical
and information-theoretic traditions from the point of view of their
representational frameworks. I argue that it is at this level, at the level of
its framework, that the quantum logical tradition has retained its centrality
to Bub's thought. It is further argued that there is implicit in the quantum
information-theoretic tradition a set of ideas that mark a genuinely new
alternative to the framework of quantum logic. These ideas are of considerable
interest for the philosophy of quantum mechanics, a claim which I defend with
an extended discussion of their application to our understanding of the
philosophical significance of the no hidden variable theorem of Kochen and
Specker.Comment: Presented to the 2007 conference, New Directions in the Foundations
of Physic
Quantum mechanics is about quantum information
I argue that quantum mechanics is fundamentally a theory about the
representation and manipulation of information, not a theory about the
mechanics of nonclassical waves or particles. The notion of quantum information
is to be understood as a new physical primitive -- just as, following
Einstein's special theory of relativity, a field is no longer regarded as the
physical manifestation of vibrations in a mechanical medium, but recognized as
a new physical primitive in its own right.Comment: 17 pages, forthcoming in Foundations of Physics Festschrift issue for
James Cushing. Revised version: some paragraphs have been added to the final
section clarifying the argument, and various minor clarifying remarks have
been added throughout the tex
A model balancing cooperation and competition explains our right-handed world and the dominance of left-handed athletes
An overwhelming majority of humans are right-handed. Numerous explanations
for individual handedness have been proposed, but this population-level
handedness remains puzzling. Here we use a minimal mathematical model to
explain this population-level hand preference as an evolved balance between
cooperative and competitive pressures in human evolutionary history. We use
selection of elite athletes as a test-bed for our evolutionary model and
account for the surprising distribution of handedness in many professional
sports. Our model predicts strong lateralization in social species with limited
combative interaction, and elucidates the rarity of compelling evidence for
"pawedness" in the animal world.Comment: 5 pages of text and 3 figures in manuscript, 8 pages of text and two
figures in supplementary materia
Interfacial mixing in heteroepitaxial growth
We investigate the growth of a film of some element B on a substrate made of
another substrance A in a model of molecular beam epitaxy. A vertical exchange
mechanism allows the A-atoms to stay on the growing surface with a certain
probability. Using kinetic Monte Carlo simulations as well as scaling
arguments, the incorporation of the A's into the growing B-layer is
investigated. Moreover we develop a rate equation theory for this process. In
the limit of perfect layer-by-layer growth, the density of A-atoms decays in
the B-film like the inverse squared distance from the interface. The power law
is cut off exponentially at a characteristic thickness of the interdiffusion
zone that depends on the rate of exchange of a B-adatom with an A-atom in the
surface and on the system size. Kinetic roughening changes the exponents. Then
the thickness of the interdiffusion zone is determined by the diffusion length.Comment: 11 pages, 11 figure
Kochen-Specker theorem for a single qubit using positive operator-valued measures
A proof of the Kochen-Specker theorem for a single two-level system is
presented. It employs five eight-element positive operator-valued measures and
a simple algebraic reasoning based on the geometry of the dodecahedron.Comment: REVTeX4, 4 pages, 2 figure
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